Electric lamp



(No Model.)

ls. B. COBB. ELECTRIC LAMP.

Patented'Jan. l21

Zin esse.

UNITED STATES 'PATENT' :Ormea SAM B. COBB, F CHICAGO, ILLINOIS.

ELECTRIC LAMP;

SPECIFICATION forming part of Letters Patent No 419,829, dated January 21, 1890. Application filed March 10, 1888- -Serial No. 266,300. (No model.)

To all h-071i it may concern:

Be it known that I, SAM B. COBB, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have 5 invented a new and useful Improvement in Electric Lamps, of `which the following is a h specification.

Myinvention relates particularly to an iin- `yprovemcnt in incandescent electric lamps,

ro whereby the life of the substance rendered incandescent by the current to produce the light is greatly prolonged, either initially-- that is, by the application of my improvement before the lamp has been used--or by the ap- 1' 5plication thereof to lamps which have become high tension witlruse, or which are originally high tension, whereby theyare restored vto usefulness or rendered useful'.v o

vThe life of an incandescent lamp of the genzo eral form at present in use, or length of time during which the substance Within. the lainp which, by its reduction to --an incandescent l state, affords the light, and commonly referred to as the carbon, though not necessarily z 5 composed of that material, performs its function, is supposed to be, as I understand, with the exercise of great care, and at the most, about fifteen hundred hours, though it is commonly warranted for only six hundred hours.

3o When the carbon has become impaired to an extent that the light it gives is insufficiently luminous, or to the extent of becoming .severed, When,A of course, by the consequent breaking of the circuit it gives nolight, the 3,5 lamp has to be thrown away, since' it is im` practicable to supply it with a fresh carbon.

It has been discovered that by introducing 'a supply of a suitable liquid intothe lamp to surround the terminals within it near the con- V4Q nection therewith of the loop of platinum, carbon, or thelike forming the carbon, burning out or impairment of the latter by vbecoming high tension is prevented'for an indefinite length of time, and that if the liquid be ap;

-K L plied to alamp the'carbon of which is already so impaired by use, though not severed, but- To Yillustrate my invention I have selected a common form of incandescent electric lamp, which is shown inthe accompanying drawing in sectional,elevation.` j

A is the glass bulb. of -an incandescent 'lamp A, (shown in the drawing as of the kind in which the bulb is practically exhausted of 'Huid contents5) B, the stopper, and C a concavity or glass chamber in the narrow end of the bulb, and through small apertures in' which the wires r and r', for connection in the circuit and fitting closely inthe apertures, extend, and to which, respectively, the ends of the platinum, carbon, or. other suitable thread D are fastened.

I introduce into the chamber C'a liquid E which is non-conductive ofelectricity to an extentrthat it willinot short-circuit the current and surrounds the term-mms and 7" within the chamber. My experiments have been principally confined to oleaglnous l1qnids, and more especially to mineral oils,

though, of course, any liquid which will produce the results, or either of them, abovedescribed is included as within the spirit of vmy invention. Of the oils I have used in my experiments parafiine-oil has been subjected to the longest tests, which have been solong as to satisfy me that my improvement renders an incandescent lamp, as to the carbon por- Y tion thereof, practically'indestructible by preventing its becominghigh tension.

rlhe liquid introduced for my purpose may be in a quantity to iill the chamber C, though I fill it only about one-third full, and though it is consumed, its decrease is hardly perceptible, so that I am led topresume that it would require several years to emptythe chamber C of an ordinary lamp one-third full of oil.v

I do not pretend to account with absolute' certainty for the effect produced by my improvement, though the theory is advanced 'and believed to be correct that as the liquid formsa seal it prevents the access of air 'to' ,the interior of the bulb, which would account` ,for they non-consumption of a fresh carbon,

and that the liquid gains access to the' carbon, (probably by capillary attraction,) and when vthe latter is impaired'softens or annealsi and` thereby restoresy its quality of resistance the quantity decreases, thus indicating that.v

to the normal condition. Not being., pre' pared, however-,te vouch; as a matt'erof certainty for any theory, I merely herein 'present the means andthe result thereby attained as constituting-my invention. p 'What I lclairna's-new, and desire to secure by Letters Patent, is

v1.` An incandescent electric lamp comprising the usual' bulb, carbon, and conducting- Wires, and provided on the exterior of the bulbwith a non-conducting liquid contained in asin glechamber and surrounding both the \V1I`S.

2. In an incandescent electric lamp, the combination of the glass bulb A', a conductor r o", extending into the bulb through apertures which t closely around the conductor and having the carbon D in circuit, and a supply of liquid which acts upon the carbon, as described, contained in a, single chamber and applied to the conductor outside the bulb over the sai d apertures, substantially as described.

3. In an incandescent electric lamp, the l combination pf a glass bultna conductor ex- 'surrounding the conducting-wires, substantially as described.

tendinginto the bulb through apertures which. 2 5

`taining a'supply of oil which acts upon the carbon, as described, mounted upon the bulb 4. In an incandescent electric lamp, the combination of the bulb A', having a charn- -ber C, provided with 'apertures leading into the bulb, a conductor 1 rr', extending into the bulb through the said apertures which fit closely around the conductor and having,r a carbon D in circuit, and a supply in the chamber C of a liquid E inherently non-conductive of electricity to fan extent that will not shortcircuit the current,wh ich forms a seal around lthe conductor at the said apertures and acts upon the carbon, substantially as described.

SAM B. COBB. In presence of- J. W. DYRENFORTH, CHA-s. E. GAYLORD. 

